using System;

using System.Linq;

using System.Diagnostics;

using System.Text;

public class Program

{

    public static void Main()

    {

        var ss = Enumerable

                    .Range(1, 5000)

                    .Select(_ => new { 

                                    s1 = Guid.NewGuid().ToString(), 

                                    s2 = Guid.NewGuid().ToString(),

                                    s3 = Guid.NewGuid().ToString(),

                                    s4 = Guid.NewGuid().ToString(),

                                    s5 = Guid.NewGuid().ToString(),

                                    s6 = Guid.NewGuid().ToString(),

                    })

                    .ToList();

        var sw = Stopwatch.StartNew();

        ss.ForEach(_ => Add2(_.s1, _.s2, _.s3, _.s4, _.s5, _.s6));

        Console.WriteLine("String Builder: {0}", sw.Elapsed);

        sw = Stopwatch.StartNew();

        ss.ForEach(_ => Add1(_.s1, _.s2, _.s3, _.s4, _.s5, _.s6));

        Console.WriteLine("String  Concat: {0}", sw.Elapsed);

    }

    static string Add1(string s1, string s2, string s3, string s4, string s5, string s6) { return s1 + s2 + s3 + s4 + s5 + s6; }

    static string Add2(string s1, string s2, string s3, string s4, string s5, string s6)

    {

        var sb = new StringBuilder();

        sb.Append(s1);

        sb.Append(s2);

        sb.Append(s3);      

        sb.Append(s4);      

        sb.Append(s5);      

        sb.Append(s6);

        return sb.ToString();

    }

}